Infradian rhythmic variations of salivary estradioland progesterone in healthy men

Abstract Background. Circadian and circannual rhythms of sex steroids in men have been well described, but infradian dynamics of estradiol and progesterone in men are unknown. These hormones play a role in the physiology as well as in the pathophysiology of various clinical entities, and their chronobiology might be of importance. Aim. Infradian dynamics of salivary estradiol, testosterone, and progesterone were analysed for the presence of cyclic patterns. Subjects and methods. Five young healthy men collected saliva samples for 30 consecutive days. Salivary estradiol, testosterone, and progesterone were measured using radioimmunoassay. Analysis of Rhythmic Variance (ANORVA) was used and potential period lengths of 3–15 days were evaluated. Results. No infradian rhythms were found in testosterone and progesterone, but a significant (p < 0.03) rhythm at a period length of 12 days was found in salivary estradiol levels. Discussion. We believe that this is the first study to describe a 12-day (duodecimal) rhythm of salivary estradiol in men. This finding might be of importance for physiological and pathophysiological research, though the pattern needs to be investigated in larger studies.